DCIS accounts for about 20% of breast cancer cases. Although associated mortality rates are low, DCIS can recur, and about half of recurrences are invasive cancers.

This new study shows that treatment, including removal of the cancer followed by radiotherapy to the affected breast, leads to low rates of recurrence. Researchers said the study also offers clues as to which patients need more aggressive treatments and which could safely receive fewer treatments.

The research was led by Icro Meattini, MD, a clinical oncologist at the University Hospital of Florence, Italy. He said, “A diagnosis of DCIS can be frightening, but also confusing. Although we know that few patients will go on to develop invasive cancer, we don’t know which ones they will be, and so we offer treatments such as surgery, radiotherapy, and sometimes hormone therapy.”

He continued, “We wanted to look in detail at women treated for DCIS to see if there are any clues about who is most at risk of a recurrence, and to understand the risks and benefits of different treatments.”

Methods and Findings

Dr. Meattini and his colleagues studied 1,072 patients with DCIS treated at nine hospitals in Italy from 1997 to 2012. All had received the recommended treatment of breast-conserving surgery followed by radiotherapy. Researchers compared the rate of recurrence at 5 years and 10 years after diagnosis, as well as survival rates.

Overall, they found that patients had a 3.4% risk of a recurrence after 5 years and a 7.6% risk after 10 years. They also found that patients' chances of dying from breast cancer were 0.7% after 5 years and 0.9% after 10 years.

The team explained that patients who were postmenopausal when they were diagnosed were less likely to suffer a recurrence compared to premenopausal patients. Recurrence was also less common among patients with ER-positive cancers. Being postmenopausal and having ER-positive DCIS halved the risk of a local recurrence. Patients with a final surgical margin of less than 1 mm had a 3 times higher risk of recurrence.

Study Implications

“The results of this study should offer all DCIS patients reassurance that the risk of their cancer returning is very low, if they are treated with breast-conserving surgery followed by radiotherapy,” Dr. Meattini added.

“For patients who are postmenopausal or whose cancer is ER-positive, the likelihood of recurrence is even lower. Where the results of surgery reveal very small cancer-free margins, the risk of recurrence is higher,” he continued.

“Now we need to do more research to find out if lower-risk patients can safely be given less treatment or even no treatment, as well as studies on how best to treat higher-risk patients. In the meantime, it’s vital that patients receive the treatment best suited to their individual cancer and their particular circumstances,” he concluded.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.